结题报告

#include <iostream>
#include <stack>
#include <cstio>
#include <cstring>
using namespace std;
stack <float> data;
stack <char> symbol;
int b[5][6];
int change(char a){
    int symbol_index;
    switch(a){
        case ‘+‘:symbol_index=1;break;
        case ‘-‘:symbol_index=2;break;
        case ‘*‘:symbol_index=3;break;
        case ‘/‘:symbol_index=4;break;
        case ‘@‘:symbol_index=5;break;
    }
    return symbol_index;
}
int main(){
    memset(b,0,sizeof(b));
    b[3][1]=b[3][2]=b[4][1]=b[4][2]=b[1][5]=b[2][5]=b[3][5]=b[4][5]=1;
    string a;
    cin >> a;
    symbol.push(‘@‘);
    float index=0;
    for(int i=0;i<a.length();i++){
        if(a[i]==‘#‘){
            data.push(index);
            break;
        }
        if(a[i]<=‘9‘&&a[i]>=‘0‘){
            index*=10;
            index+=a[i]-‘0‘;
        }
        else{
            data.push(index);
            index=0;
            int symbol_index;
            symbol_index=change(a[i]);
            while(b[symbol_index][change(symbol.top())]==0){
                float b=data.top();
                data.pop();
                float a=data.top();
                data.pop();
                switch(symbol.top()){
                    case ‘+‘:data.push(a+b);break;
                    case ‘-‘:data.push(a-b);break;
                    case ‘/‘:data.push(a/b);break;
                    case ‘*‘:data.push(a*b);break;
                }
                symbol.pop();
            }
            symbol.push(a[i]);
        }
    }
    while(symbol.top()!=‘@‘){
        float b=data.top();
        data.pop();
        float a=data.top();
        data.pop();
        switch(symbol.top()){
            case ‘+‘:data.push(a+b);break;
            case ‘-‘:data.push(a-b);break;
            case ‘/‘:data.push(a/b);break;
            case ‘*‘:data.push(a*b);break;
        }
        symbol.pop();
    }
    printf("%.4f",data.top());
    return 0;
}